EP0228010B1 - Composition phosphorèe luminescente, procédé pour sa préparation et lampe fluorescente l'utilisant - Google Patents

Composition phosphorèe luminescente, procédé pour sa préparation et lampe fluorescente l'utilisant Download PDF

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EP0228010B1
EP0228010B1 EP86117408A EP86117408A EP0228010B1 EP 0228010 B1 EP0228010 B1 EP 0228010B1 EP 86117408 A EP86117408 A EP 86117408A EP 86117408 A EP86117408 A EP 86117408A EP 0228010 B1 EP0228010 B1 EP 0228010B1
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phosphor
sulfate
alkaline earth
earth metal
weight
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EP0228010A1 (fr
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Masahiko Kasei Optonix K.K. Yoshino
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Kasei Optonix Ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
    • C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/66—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing germanium, tin or lead
    • C09K11/668—Sulfates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • C09K11/7741—Sulfates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7783—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals one of which being europium
    • C09K11/7784—Chalcogenides
    • C09K11/7787—Oxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/38—Devices for influencing the colour or wavelength of the light
    • H01J61/42—Devices for influencing the colour or wavelength of the light by transforming the wavelength of the light by luminescence
    • H01J61/44—Devices characterised by the luminescent material

Definitions

  • the present invention relates to a luminescent phosphor composition, a process for its preparation and a fluorescent lamp employing it. More particularly, the present invention relates to a luminescent phosphor composition composed of a phosphor and a sulfate of alkaline earth metal, which maintains an extremely high level of luminance in spite of a large content of such a non-luminescent material and which is very inexpensive, a process for its preparation and a fluorescent lamp wherein such a luminescent phosphor composition is used as a fluorescent layer.
  • Phosphors are usually expensive as compared with ordinary chemical materials, since they have a special property to convert invisible radiant energy to a visible light.
  • substantial amounts of rare earth elements or noble metal elements have been used as raw materials to satisfy various properties.
  • 4,069,441 discloses an electric gas discharge lamp wherein a layer consisting of a mixture of a phosphor and a white material having a small absorption for ultraviolet rays, such as barium sulfate, calcium pyrophosphate or magnesium oxide, is provided on a glass tube, and a layer consisting solely of a phosphor is laminated thereon, and the layer consisting of the mixture is formed so that the ratio of the amount of the white material to the amount of the phosphor increases towards the glass tube.
  • a related technique is also disclosed in Japanese Unexamined Patent Publication No. 128452/1982.
  • the above-mentioned mixture of the phosphor and the white material has a difficulty such that the decrease in the luminance is substantially large from the practical point of view, and in order to minimize this decrease or in order to provide other effects, cumbersome means such as the formation of the special layer structure as shown in the above publications, is required. In many cases, the amount of the use of the mixture is restricted to a level of not higher than a few percent by weight.
  • none of the conventional techniques is capable of substantially reducing the costs for such luminescent phosphor materials without substantial reduction of the luminance of the luminescent phosphor materials.
  • the present inventors have conducted various researches on the combination of inexpensive non-luminescent materials and expensive phosphors to attain the above object, and as a result, have found it possible to obtain a luminescent phosphor material satisfying the above object by mixing a phosphor with a sulfate of alkaline earth metal, followed by sintering.
  • the present invention has been accomplished on the basis of this discovery.
  • the present invention provides a luminescent phosphor composition composed essentially of particles formed by fusion of a phosphor and a sulfate of alkaline earth metal, wherein the total amount of the fused and non-fused sulfate is within a range of from 5 to 95% by weight.
  • the present invention also provides a process for producing a luminescent phosphor composition, which comprises sintering a phosphor or a phosphor raw material and a sulfate of alkaline earth metal in their coexistent state.
  • the present invention provides a fluorescent lamp having a fluorescent layer which contains a luminescent phosphor composition composed essentially of particles formed by fusion of a phosphor and a sulfate of alkaline earth metal.
  • Figure 1 is a graph showing the relation between the relative luminance under excitation with ultraviolet rays and the reduction in the costs of material, when the proportions of the phosphor and the alkaline earth metal sulfate were varied, wherein curves 1 and 2 represent luminescent phosphor compositions of the present invention, and curve 3 represents a mixture according to a conventional technique.
  • Figure 2 is a graph showing the relation between the emitted color (x-value) and the relative luminance with respect to a phosphor, a luminescent phosphor composition of the present invention and a luminescent phosphor composition or mixture other than the present invention, under excitation with ultraviolet rays.
  • Figure 3 is a graph showing the relation between the sintering temperature (°C) during the preparation of a luminescent phosphor composition of the present invention and the relative luminance (%).
  • Figure 4-a is an electron microscopic photograph illustrating the particle structure of a mixture.
  • Figures 4-b and 4-c are electron microscopic photographs each illustrating the particle structure of a luminescent phosphor composition of the present invention.
  • Figures 5-a, 5-b and 5-c are electron microscopic photographs each illustrating the particle structure of a luminescent phosphor composition of the present invention.
  • Figures 6-a and 6-b are X-ray diffraction spectra of luminescent phosphor compositions of the present invention.
  • the luminescent phosphor composition of the present invention may be prepared, for example, by the following process (hereinafter referred to as process 1).
  • a phosphor and a sulfate of alkaline earth metal are thoroughly mixed, and then the mixture is sintered at a temperature within a range of from 550 to 1600°C.
  • the phosphor to be used in the present invention may be any one of conventional phosphors, but from the viewpoint of the sintering atmosphere, etc., an oxide-type phosphor containing oxygen as a matrix element, such as an oxide, an oxysulfide, a vanadate, a silicate, a phosphate, an aluminate or a borate, is practically most conveniently used. Namely, such an oxide phosphor is suitable as a phosphor to be sintered in an oxygen atmosphere, in a neutral atmosphere or in a weakly reducing atmosphere.
  • the present invention is effectively applied to a phosphor which contains at least one of rare earth elements and noble metal elements with a view to effective reduction of the costs for material, and the effectiveness is remarkable particularly when applied to phosphors containing greater amounts of these elements.
  • the present invention is applied to rare earth oxide phosphors containing europium as activator (i.e. Ln2O3:Eu phosphors wherein Ln is at least one of Y, Gd, La and Lu) as the most expensive oxide phosphors among various phosphors used in large amounts for lamps, the effectiveness is particularly remarkable.
  • the sulfate of alkaline earth metal in the present invention is a sulfate of at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca) and magnesium (Mg).
  • Representative examples include barium sulfate (BaSO4), strontium sulfate (SrSO4) and Calcium sulfate (CaSO4).
  • These alkaline earth metal sulfates are usually subjected to sieving prior to mixing with the phosphor, to disintegrate agglomerates and obtain small particles, which will then be used. The mixing of the two components is thoroughly conducted in a mortar or mill in either a dry system or a wet system.
  • the mixture is put in a heat resistant container and sintered at the above-mentioned temperature.
  • This sintering is conducted usually at a temperature lower than the melting point of the phosphor and the alkaline earth metal sulfate to be used.
  • the sintering time is usually within a range of from a few ten minutes to several hours.
  • the atmosphere for this sintering may be a sintering atmosphere commonly employed for the preparation of ordinary phosphors. Among then, it is preferred to select a condition under which the alkaline earth metal sulfate hardly undergoes a change.
  • the sintering temperature is preferably within a range of from 800 to 1550°C. It is advisable to add a fluxing agent when the above raw materials are mixed. It is particularly preferred to add a compound containing at least one of barium, phosphorus and boron. By the incorporation of such a fluxing agent, it is possible to obtain a luminescent phosphor composition having excellent luminance and
  • the phosphor raw material and the alkaline earth metal sulfate are simply mixed in a dry or wet system, followed by sintering to obtain a fused product.
  • the alkaline earth metal sulfate is usually agglomerated in the form of large particles having a size of at least 10 ⁇ m although the primary particle size is about 1 ⁇ m, and it is very difficult to completely disintegrate such agglomerates. If it is mixed and sintered with the phosphor and the flux in such an agglomerated state, coarse fused particles will be formed.
  • process 2 Another process whereby luminescent phosphor compositions of the present invention can be produced to have proper particle sizes with a narrow particle size distribution, is as follows (hereinafter referred to as process 2).
  • a solution of oxalic acid or a water-soluble oxalate and a solution of sulfuric acid or a water soluble sulfate are added together or separately to an aqueous solution containing both a compound containing at least one metal element for constituting a phosphor matrix and an alkaline earth metal salt, to form precipitates of the oxalate of the metal element for constituting the phosphor matrix and the sulfate of the alkaline earth metal, and the precipitates are used as the main component for a phosphor raw material.
  • the phosphor raw material is then sintered.
  • rare earth material as the phosphor raw material is composed mainly of an oxide as the main starting material.
  • an aqueous oxalic acid solution to an aqueous solution of a water-soluble rare earth salt (a chloride, nitrate, a sulfate, etc.) or to an aqueous solution obtained by dissolving its oxide, hydroxide or carbonate in an acid (such as hydrochloric acid, sulfuric acid or nitric acid), to precipitate a rare earth metal oxalate, which is then baked at a temperature of from 800 to 1000°C to an oxide.
  • This treatment is particularly preferred for a phosphor containing a small amount of a rare earth activator in a rare earth host material, such as La2O3:Ln ⁇ or Ln2O2S:Ln ⁇ .
  • the alkaline earth metal sulfate can readily be formed by adding sulfuric acid to an aqueous solution of a water soluble alkaline earth metal salt (such as a nitrate or halides but fluoride), or to an aqueous solution obtained by dissolving its oxide or carbonate in hydrochloric acid or nitric acid.
  • a water soluble alkaline earth metal salt such as a nitrate or halides but fluoride
  • the alkaline earth metal sulfate is extremely stable in water and hardly soluble even in an acid.
  • a solution of oxalic acid or a water-soluble oxalate such as ammonium oxalate, diethyl oxalate or an alkali metal oxalate, preferably ammonium oxalate or diethyl oxalate
  • a solution of sulfuric acid or a water-soluble sulfate such as ammonium sulfate or an alkali metal sulfate, preferably ammonium sulfate
  • a solution containing a water-soluble rare earth salt containing a rare earth element for constituting a matrix metal element for the phosphor to form precipitates of the oxalate of the matrix metal element and the sulfate of the alkaline earth metal.
  • the solution is usually stirred.
  • Precipitates having a desired granularity may be formed by controlling the stirring condition, the concentration of the solution or the rate of adding oxalic acid or sulfur
  • the precipitates thus obtained are put in e.g. a heat resistant container and sintered, to fuse the phosphor and the alkaline earth metal sulfate.
  • This sintering can be conducted in the same manner as the above-mentioned sintering.
  • a phosphor or a phosphor raw material being a solid solution of an activator in at least one of host materials and a sulfate of alkaline earth metal, are mixed in such a manner that the sulfate of alkaline earth metal is dispersed in a solvent and in that state, deposited on the phosphor or on the phosphor raw material to form a composite material, which is then dried and sintered at a temperature within a range of from 550 to 1600°C (hereinafter referred to as process 3).
  • the sulfate of alkaline earth metal is dispersed in a solvent before it is mixed with the phosphor or the phosphor raw material.
  • the dispersion may be conducted simply by stirring the sulfate in a solvent. However, it is preferred to preliminarily disperse it mechanically by a ballmill or the like, or to facilitate the dispersion in the solvent by a supersonic wave.
  • the solvent it is common to employ water.
  • an organic solvent such as methanol, ethanol or isopropyl alcohol, may be employed.
  • the sulfate of alkaline earth metal dispersed in the solvent is then thoroughly mixed with the phosphor or the phosphor raw material. The mixing is conducted usually under stirring.
  • the sulfate of alkaline earth metal and the phosphor or the phosphor raw material undergo physical adsorption in the solvent depending upon the combination, whereby the sulfate of alkaline earth metal is uniformly deposited on the particles of the phosphor or the phosphor raw material to form a kind of a composite material.
  • a small amount of an organic binder is preferably employed to improve the adhesion.
  • an acrylic resin As such an organic binder, an acrylic resin, a polyvinyl acetate resin, a polyvinyl butyral resin, a synthetic rubber latex, a polyvinyl pyrrolidone, a polyvinyl alcohol or gelatin is effective.
  • the composite material thus obtained is subjected to drying treatment, and then sintered in e.g. a heat resistant container.
  • This sintering can be conducted in the same manner as in the above-mentioned sintering.
  • a precursor which is capable of being converted to a sulfate of alkaline earth metal is capable of being converted to a sulfate of alkaline earth metal.
  • the sulfate of alkaline earth metal for the purpose of the present invention includes such a precursor.
  • a precursor there may be mentioned a combination of an inorganic salt such as a carbonate or nitrate or an organic salt such as an acetate citrate or oxalate, of alkaline earth metal, and a sulfate such as ammonium sulfate.
  • Figure 3 is a graph showing the relation between the sintering temperature (°C) for the preparation of the luminescent phosphor compositions of the present invention and the relative luminance (%) under excitation with ultraviolet rays having a wavelength of 253.7 nm.
  • point A represents a Y2O3:Eu phosphor (relative luminance of this phosphor is evaluated to be 100%)
  • curve 1 represents a case wherein a mixture as the starting material obtained by mechanically mixing 50 parts by weight of a Y2O3:Eu phosphor and 50 parts by weight of BaSO4, is sintered
  • curve 2 represents a case wherein a mixture as the starting material obtained by mixing 50 parts by weight of an Eu-containing Y2O3 as a raw material for a Y2O3:Eu phosphor and 50 parts by weight of BaSO4, was sintered.
  • the sintering temperature is usually at least 550°C, preferably at least 800°C, more preferably at least 1000°C.
  • the upper limit for the sintering is usually 1600°C, preferably 1550°C, by an ordinary sintering method, although the sintering temperature may vary depending on the sintering time.
  • the luminescent phosphor composition can be obtained as described above.
  • the luminescent phosphor composition of the present invention exhibits an extremely high luminance as compared with a mere mixture of a phosphor and an alkaline earth metal sulfate, or as compared with a luminescent phosphor composition obtained in the same manner as described above by using a phosphor and a material other than the alkaline earth metal sulfate.
  • Figure 2 shows the relation between the emitted color (x-value in the CIE chromaticity coordinates) and the relative luminance (%) with respect to a (Y.Gd)2O3:Eu phosphor, a mere mixture of this phosphor with an alkaline earth metal sulfate and a luminescent phosphor composition obtained from the mixture, under excitation with ultraviolet rays of 253.7 nm.
  • point A represents the emitted color and the relative luminance of the (Y.Gd)2O3:Eu phosphor
  • other black circles ( ⁇ ) indicate the respective values in the cases where 50 parts by weight of this phosphor was mixed with 50 parts by weight of the respective materials as identified in the Figure, followed by sintering at about 1200°C for 4 hours.
  • the black triangles ( ⁇ ) in the Figure indicate the respective values of mere mixtures obtained by mechanically mixing 50% by weight of the above phosphor with 50% by weight of the respective materials identified in the Figure.
  • the luminescent phosphor composition of the present invention composed of the above phosphor and BaSO4 or SrSO4, show no substantial difference in the emitted color and relative luminance from point A for the 100% phosphor despite they contain a non-luminescent material in such a large amount as 50% by weight.
  • the luminescent phosphor compositions outside the present invention wherein ZnO, Al2O, BaHPO4, Ca3(PO4)2, Al2(SO4)3 and AlPO4 were incorporated, respectively, were inferior in that the relative luminance was lower by from 20 to 80%, or a substantial change was observed in the emitted color, whereby the object of the present invention was not attained, and the effect of the present invention was not obtained.
  • the mere mixture of the phosphor with BaSO4 or SrSO4, as indicated by the black triangle ( ⁇ ) had a luminance lower by about 20% than the point A or the luminance of the luminescent phosphor composition of the invention, since such a mixture contained a non-luminescent material in a large amount.
  • the luminance of such a mixture certainly shows the effect as disclosed in U.S. Patent No. 4,069,441, but the decrease in the luminance as much as 20% makes the mixture practically useless.
  • Figure 1 shows the relation between the relative luminance (%) under excitation with ultraviolet rays of 253.7 nm and the reduction (%) in the costs of material when the proportions (% by weight) of the phosphor and the alkaline earth metal sulfate were varied in the luminescent phosphor compositions of the present invention.
  • curve 1 represents a luminescent phosphor composition of the present invention composed of a Y2O3:Eu phosphor and BaSO
  • curve 2 represents a luminescent phosphor composition of the present invention composed of a (Y,Gd)2O3:Eu phosphor and BaSO
  • curve 3 represents a conventional mixture obtained by mechanically mixing a Y2O3:Eu phosphor and BaSO4.
  • Curve 4 shows the relation between the composition of the Y2O3:Eu phosphor and BaSO4 and the reduction (%) in the costs of material.
  • the luminescent phosphor compositions of the present invention represented by curves 1 and 2 show a high luminance, for instance, higher by at least 20% at the alkaline earth metal content of 50% by weight, or by at least 30% at the alkaline earth metal content of 80% by weight, than the conventional mixture represented by curve 3.
  • a surprising effect was obtained in that the luminance was substantially equal or even higher by about 7% as compared with the luminance of the phosphor itself containing no non-luminescent material.
  • the reduction in the costs of material in such a case can be as high as 76% at the maximum.
  • the luminescent phosphor composition of the present invention has an alkaline earth metal sulfate content of from 5 to 95% by weight, preferably from 10 to 95% by weight, and for the practical purpose, a range of from 25 to 90% by weight is recommended.
  • the sulfate of alkaline earth metal used in the present invention is preferably a sulfate of barium, strontium or calcium. From the viewpoint of the above-mentioned effect, the specific gravity and the thermal stability, it is practically preferred to employ a sulfate of alkaline earth metal wherein the alkaline earth metal is, or is composed essentially of, at least one of barium and strontium.
  • the sintering temperature is preferably from 800 to 1550°C, more preferably from 1000 to 1500°C.
  • the effects of the present invention have been described with respect to the luminescent phosphor compositions excited with ultraviolet rays. However, similar effects are obtainable under excitation with electron beams. This indicates that in the present invention, the alkaline earth metal sulfate such as BaSO4 is used not merely for the ultraviolet reflecting effect as in the conventional technique.
  • Figure 4-a shows an electron microscopic photograph (3000 magnifications) of a mixture obtained by mixing 50% by weight of a Y2O3:Eu phosphor and 50% by weight of BaSO4 particles
  • Figure 4-b shows a similar electron microscopic photograph of a luminescent phosphor composition of the present invention obtained by sintering the mixture
  • Figure 4-c shows an electron microscopic photograph (3000 magnifications) of a luminescent phosphor composition of the present invention obtained by sintering a mixture prepared by mixing 50% by weight of a (Y.Gd)2O3:Eu phosphor and BaSO4 particles.
  • Figures 5-a and 5-b show electron microscopic photographs of the luminescent phosphor compositions of the present invention obtained by sintering, under different conditions, a mixture comprising 50% by weight of a Y2O3:Eu phosphor and 50% by weight of BaSO4 particles.
  • Figure 5-c shows an electron microscopic photograph (30000 magnifications) of a luminescent phosphor composition of the present invention obtained by sintering a co-precipitated product obtained by co-precipitating 50% by weight of the raw material for a Y2O3:Eu phosphor and 50% by weight of BaSO4.
  • Samples in Figures 5-a, 5-b and 5-c were measured after deposition of gold.
  • Figure 6-a shows an X-ray diffraction spectrum of the luminescent phosphor composition of the present invention shown in Figure 4-b.
  • Figure 6-b shows an X-ray diffraction spectrum of the luminescent phosphor composition of the present invention shown in Figure 4-c.
  • the luminescent phosphor composition of the present invention obtained by the above-mentioned process, is represented by the formula (Ln,Eu)2O3 ⁇ xM II SO4 (wherein Ln is at least one of Y, Gd, La and Lu, M II is an alkaline earth metal, and x is a positive number showing the proportion).
  • the particles formed by fusion of a phosphor and a sulfate of alkaline earth metal in the present invention include, not only those obtained by sintering the two components at a temperature of at least 550°C, preferably at least 800°C, wherein the boundaries of the two components are not distinct as shown in Figure 4-b, but also those wherein the two components are sintered to each other as shown in Figures 5.
  • the luminance of the luminescent phosphor composition thereby obtained was equal to or even higher than the composition containing no such an activator element.
  • an activator element used in a trace amount, europium (Eu), lead (Pb), terbium (Tb), Cerium (Ce) and manganese (Mn) are recommended.
  • the activator element is preferably at least one of europium and lead.
  • the luminescent phosphor composition of the present invention is capable of providing an emission having an extremely high luminance under excitation with ultraviolet rays. Accordingly, by using this luminescent phosphor composition, it is possible to produce an extremely useful fluorescent lamp in accordance with a conventional method. In particular, with the luminescent phosphor composition of the present invention, it is possible to remarkably reduce the costs for the phosphor having a high luminance and containing a rare earth element or a noble metal element, and it is recommended to use the luminescent phosphor composition of the present invention for the high color rendering fluorescent lamp in which such a phosphor is used in a large amount.
  • the fluorescent layer contains a blue-emitting material having a peak emission wavelength within a range of from 430 to 475 nm, a green-emitting material having a peak emission wavelength within a range of from 520 to 560 nm and a red-emitting material having a peak emission wavelength within a range of from 595 to 630 nm, and at least one of the above color emitting materials is made of the luminescent phosphor composition of the present invention.
  • a cerium terbium-activated lanthanum phosphate phosphor such as LaPO4:
  • a bluish green emitting material having a peak emission wavelength within a range of from 480 to 500 nm may be incorporated.
  • a bivalent europium-activated strontium aluminate phosphor such as 4SrO ⁇ nAl2O3:Eu2+, wherein 5 ⁇ n ⁇ 8
  • a bivalent europium-activated alkaline earth metal borophosphate phosphor such as mM II O ⁇ (1-n)P2O5
  • a luminescent phosphor composition of the present invention wherein at least one of the above phosphors and a sulfate of alkaline earth metal are fused, it is possible to substantially reduce the amount of the phosphor required.
  • an oxide type phosphor includes a europium-activated rare earth oxide phosphor, and a cerium terbium-activated rare earth silicate phosphor.
  • the surprising effects of the luminescent phosphor composition of the present invention include not only the improvement in the luminance of the fused phosphor, but also an improvement in the luminance of other phosphors mechanically mixed but not fused with the luminescent phosphor composition of the present invention.
  • a high color rendering fluorescent lamp of the present invention having a fluorescent layer obtained by mixing (Ln,Eu)2O3 ⁇ BaSO4 as the luminescent phosphor composition of the present invention with the above green-emitting phosphor and the above blue-emitting phosphor, requires a less amount of the (Ln,Eu)2O3 phosphor to obtain the same emitted color as the conventional high color rendering fluorescent lamp containing no BaSO4, and yet requires less amounts of the green and blue-emitting phosphors. This is evidenced by a working Example given hereinafter.
  • a suitable phosphor which can be combined most stably or readily with an alkaline earth metal sulfate to form a luminescent phosphor composition of the present invention.
  • a typical example of such a phosphor is a red-emitting europium-activated rare earth oxide phosphor. Therefore, in the following Examples, fluorescent lamps wherein this phosphor is employed for the luminescent phosphor composition of the present invention, are described. However, the present invention is by no means restricted to such specific Examples.
  • Oxalate precipitates were prepared by using 76 parts by weight of gadolinium oxide (Gd2O3), 20 parts by weight of yttrium oxide (Y2O3) and 4 parts by weight of europium oxide (Eu2O3), and the precipitates were baked at 1000°C for 3 hours to obtain an oxide represented by the formula (Gd,Y,Eu)2O3. Then, 50 parts by weight of this (Gd,Y,Eu)2O3 and 50 parts by weight of barium sulfate (BaSO4, guaranteed reagent) were mixed, and a fluxing agent (1% by weight of BaCl2 ⁇ 2H2O and 0.1% by weight of H3BO3).
  • Gd2O3 gadolinium oxide
  • Y2O3 yttrium oxide
  • Eu2O3 europium oxide
  • BaSO4 barium sulfate
  • Example 2 By using the above oxide only, a standard product was prepared in the same manner as in Example 1. The relative luminance obtained from the ultraviolet measurements and the reduction in the costs of material are shown in Table 1. There was no change observed in the emitted color. The reduction in the cost of material was calculated on the basis of the price at which each material is usually commercially available, i.e. 42,000 yen/kg as the price for (Y,Eu)2O3 and 2,000 yen/kg as the price for BaSO4.
  • An oxide represented by the formula (Y,Eu)2O3 was prepared in the same manner as in Example 1 except that 94.6 parts by weight of yttrium oxide (Y2O3) and 5.4 parts by weight of europium oxide (Eu2O3) were used as raw materials. Then, 50 parts by weight of this (Y,Eu)2O3 and 50 parts by weight of barium sulfate (BaSO4) were mixed, and then treated in the same manner as in Example 2 to obtain a luminescent phosphor composition of the present invention (Y,Eu)2O3 ⁇ BaSO4. On the other hand, the above oxide (Y,Eu)2O3 alone was sintered under the same conditions to obtain a phosphor, which was used as a standard product.
  • a fluxing agent was added to 50 parts by weight of the (Y,Eu)2O3 oxide shown in Example 2 and 50 parts by weight of strontium sulfate (SrSO4), and the mixture was thoroughly mixed, then filled in a cruicible, sintered at 1350°C for 4 hours, then washed and dried to obtain a luminescent phosphor composition of the present invention (Y,Eu)2O3 ⁇ SrSO4.
  • This luminescent phosphor composition and the standard (Y,Eu)2O3 phosphor of Example 2 were subjected to ultraviolet measurements, whereby no difference was observed between the two in the luminance and the emitted colors.
  • a terbium-activated yttrium aluminate phosphor (Y3Al5O12:Tb) and 30 parts by weight of barium sulfate (BaSO4) were mixed, and a fluxing agent (1 part by weight of BaCl2 ⁇ 2H2O and 0.1 part by weight of H3BO3) was added thereto.
  • a fluxing agent (1 part by weight of BaCl2 ⁇ 2H2O and 0.1 part by weight of H3BO3
  • the mixture was thoroughly mixed, then sintered at 1200°C for 2 hours, thereafter washed and dried to obtain a luminescent phosphor composition of the present invention.
  • This composition showed a luminance under excitation with ultraviolet rays of 253.7 nm, at a level of 83% relative to 100% by the Y3Al5O12:Tb phosphor.
  • the luminance of the mere mixture before the sintering was 62%.
  • a europium-activated yttrium oxysulfide (Y2O2S:Eu) and 30 parts by weight of barium sulfate (BaSO4) were mixed, and a fluxing agent (1 part by weight of lithium phosphate) was added thereto.
  • the mixture was treated in the same manner as in Example 5 to obtain a luminescent phosphor composition of the present invention.
  • This luminescent phosphor composition showed a luminance under excitation with ultraviolet rays of 253.7 nm, at a level of 101% relative to 100% by the Y2O2S:Eu phosphor. The luminance of the mere mixture before sintering was 67%.
  • a terbium-activated yttrium silicate phosphor (Y2SiO5:Tb) and 30 parts by weight of barium sulfate (BaSO4) were mixed, and a fluxing agent (1 part by weight of Li2B4O7) was added thereto.
  • the mixture was thoroughly mixed, then sintered at 1300°C for 2 hours, thereafter washed and dried to obtain a luminescent phosphor composition of the present invention.
  • This luminescent phosphor composition showed a luminance under excitation of ultraviolet rays of 253.7 nm at a level of 110% relative to 100% by the Y2SiO5:Tb phosphor.
  • the luminance of the mere mixture before sintering was 60%.
  • a terbium-activated gadolinium oxysulfide Gd2O2S:Tb
  • barium sulfate BaSO4
  • This luminescent phosphor composition showed a luminance under excitation with ultraviolet rays of 253.7 nm at a level of 91% relative to 100% by the Gd2O2S:Tb phosphor.
  • the luminance of the mere mixture before sintering was 65%.
  • a europium-activated yttrium vanadate (YVO4:Eu) and 50 parts by weight of barium sulfate (BaSO4) were mixed, and the mixture was treated in the same manner as in Example 5 to obtain a luminescent phosphor composition of the present invention.
  • This luminscent phosphor composition showed a luminance under excitation of ultraviolet rays of 253.7 nm at a level of 83% relative to 100% by the YVO4:Eu phosphor.
  • Solution A 950 g of Y2O3 and 50 g of Eu2O3 were dissolved in a required amount of hydrochloric acid, and diluted to 10 liters.
  • Solution B 1000 g of BaCl2 ⁇ 2H2O was dissolved in water and diluted to 5 liters.
  • Solution C 600 g of oxalic acid was dissolved in 3 liters of warm water.
  • Solution D 500 g of sulfuric acid was diluted to 3 liters of a dilute sulfuric acid solution.
  • Solution D was gradually added to a mixture of solutions A and B under stirring. After the completion of the addition, solution C was gradually added thereto. After the addition, stirring was continued for a sufficient time, and then the precipitated product was washed with water, then dehydrated, filled in a quartz oven container and baked in air at 1000°C for 3 hours to obtain a raw material for sintering.
  • a fluxing agent (1.0% of BaCl2 ⁇ 2H2O and 0.1% of H3BO3) was added, and the mixture was thoroughly mixed, then filled in a cruicible and sintered at 1400°C for 4 hours. The sintered product was taken out, thoroughly washed with water, then dehydrated, dried and subjected to sieving with a 150 mesh sieve to obtain a luminescent phosphor composition.
  • Example 10 To a mixture of solutions A and B in Example 10, a mixture of solutions C and D was gradually added, and the mixture was thoroughly stirred to obtain a precipitated product, which was treated in the same manner as in Example 10 to obtain a raw material for sintering and a luminescent phosphor composition. Their granularities are shown in Table 2.
  • this raw material (Y,Eu)2O3 for sintering was mixed with 50 parts by weight of commercially available BaSO4 (150 mesh pass) and a fluxing agent (1% by weight of BaCl2 ⁇ 2H2O and 0.2% by weight of H3BO3), and the mixture was filled in a cruicible and treated under the same conditions as in Example 10 to obtain a luminescent phosphor composition.
  • the granularities of the raw material for sintering and the fluorescent phosphor composition are shown in Table 2.
  • Example 10 The precipitated product obtained in Example 10 was washed with water and dehydrated, and then a fluxing agent (0.5% by weight of BaCl2 ⁇ 2H2O and 0.1% by weight of H3BO3) was added thereto. The mixture was thoroughly mixed, then sintered at 1400°C for 4 hours in a quartz oven container, then washed with water, dried and then subjected to sieving with a 150 mesh sieve to obtain a luminescent phosphor composition. The granularities of the raw material for sintering and the luminescent phosphor composition are shown in Table 2.
  • Barium sulfate (BaSO4) was preliminarily subjected to dispersing treatment for 40 hours in a ballmill containing water and alumina balls.
  • the slurry containing 30 parts by weight of BaSO4 was poured into water, and 70 parts by weight of a co-precipitated oxide of (Y,Eu)2O3 was added thereto under stirring.
  • the mixtures was further stirred, and then a diluted solution of 0.5 part by weight of an acryl emulsion (HA-24, manufactured Nippon Acryl K.K.) was added thereto.
  • a composite material thus obtained was dehydrated, dried and subjected to sieving, and then a fluxing agent (1.0% by weight of BaCl2 ⁇ 2H2O and 0.3% by weight of H3BO3) was added thereto.
  • the mixture was thoroughly mixed, then filled in a cruicible, and sintered at 1350°C for 4 hours.
  • the sintered composition was taken out from the cruicible, thoroughly washed with water, then dehydrated, dried and subjected to sieving with a 150 mesh sieve to obtain a luminescent phosphor composition of the present invention.
  • the luminescent phosphor compositions of Examples 13 and 14 and Comparative Example 2 were measured for their granularities, particle sizes and luminance. The results are shown in Table 3.
  • a luminescent phosphor composition of the present invention comprising a europium-activated yttrium oxide phosphor and calcium sulfate, was obtained in the same manner as in Example 15 except that 27 parts by weight of calcium carbonate, 36 parts by weight of ammonium sulfate and 37 parts by weight of a co-precipitated oxide of (Y,Eu)2O3 were used.
  • a luminescent phosphor composition of the present invention comprising a europium-activated yttrium oxide phosphor and strontium sulfate, was obtained in the same manner as in Example 15 except that 40 parts by weight of strontium nitrate, 25 parts by weight of ammonium sulfate and 35 parts by weight of a co-precipitated oxide of (Y,Eu)2O3 were used.
  • the luminescent phosphor compositions of the present invention according to this process had narrow particle size distributions as compared with the Comparative Example.
  • a fluorescent lamp was prepared in accordance with a conventional method.
  • BaSO4 35 parts by weight of a green-emitting component of a LaPO4:Ce,Tb phosphor and 15 parts by weight of a blue-emitting component of a (Sr,Ca)5(PO4)3Cl:Eu2+ phosphor were thoroughly mixed, and a coating solution was prepared by using this phosphor mixture, and coated on the inside wall of a glass tube. Then, a white emitting fluorescent lamp of 30W was prepared. The coated amount was 4 mg/cm2. This fluorescent lamp had a luminous efficacy of 71 1m/W and a color rendering index of 82.
  • a white emitting fluorescent lamp was prepared in the same manner as in Example 19 by using 50 parts by weight of a red-emittig component of a fluorescent phosphor composition (Y0.1Gd0.87Eu0.03)2O3 ⁇ BaSO4, 35 parts by weight of a green-emitting component of a LaPO4:Ce,Tb phosphor and 15 parts by weight of a blue-emitting component of a BaMg2Al16O27:Eu phosphor.
  • This fluorescent lamp had luminous efficacy of 69 1m/W and a color rendering index of 83.
  • a white emitting fluorescent lamp was prepared in the same manner as in Example 19 by using 35 parts by weight of a red-emitting component of a luminescent phosphor composition (Gd0.955Eu0.045)2O3 ⁇ 0.7BaSO4, 30 parts by weight of a green-emitting component of a LaPO4:Ce,Tb phosphor, 15 parts by weight of a blue-emitting component of a Ca2B5O9Cl:Eu2+ phosphor and 30 parts by weight of a bluish green-emitting component of a 2(Ba,Ca,Sr)O ⁇ 0.9P2O5 0.1B2O3 phosphor.
  • This fluorescent lamp had a luminous efficacy of 70 1m/W and a color rendering index of 82.
  • a white emitting fluorescent lamp having a conventional composition was prepared in the same manner as in Example 19 by using 37 parts by weight of a red-emitting component of a (Y0.963Eu0.37)2O3 phosphor, 43 parts by weight of a green-emitting component of a LaPO4:Ce,Tb phosphor and 20 parts by weight of a (Sr,Ca)5(PO4)3Cl:Eu phosphor.
  • This fluorescent lamp had a luminous efficacy of 70 1m/W and a color rendering index of 82.
  • a white-emitting fluorescent lamp 25 Parts by weight of a (Y0.963Eu0.037)2O3 phosphor, 35 parts by weight of a LaPO4:Ce,Tb phosphor, 15 parts by weight of a (Sr,Ca)5(PO4)3Cl:Eu2+ and 25 parts by weight of BaSO4 (guaranteed reagent) were mixed, and a white-emitting fluorescent lamp was prepared in the same manner as in Example 19.
  • This fluorescent lamp had a luminous efficacy of 59 1m/W and a color rendering index of 79, thus the luminance was inadequate, and the color rendering index was low.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Luminescent Compositions (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)

Claims (16)

  1. Composition luminescente, composée essentiellement de particules formées par fusion d'une substance luminescente et d'un sulfate de métal alcalino-terreux, dans laquelle la teneur totale du sulfate fondu et non-fondu se situe dans la plage allant de 5 à 95% en poids.
  2. Composition selon la revendication 1, dans laquelle la teneur totale du sulfate fondu et non-fondu se situe dans la plage allant de 10 à 95% en poids.
  3. Composition selon l'une des revendications 1 ou 2, dans laquelle le métal alcalino-terreux est au moins l'un parmi le baryum, le strontium et le calcium, et dans laquelle, de préférence, le métal alcalino-terreux est, ou est composé essentiellement d', au moins l'un parmi le baryum et le strontium.
  4. Composition selon l'une des revendications 1 à 3, dans laquelle la substance luminescente contient au moins l'un parmi les métaux des terres rares et les métaux précieux.
  5. Composition selon l'une des revendications 1 à 4, dans laquelle la substance luminescente est une substance luminescente du type oxyde et, de préférence, une substance luminescente d'oxyde de terre rare contenant de l'europium comme activateur.
  6. Composition selon la revendication 4, dans laquelle le sulfate de métal alcalino-terreux contient une quantité sous forme de trace d'un élément activateur, qui est, de préférence, au moins l'un parmi l'europium et le plomb.
  7. Procédé de fabrication d'une composition luminescente, qui comprend le frittage d'une substance luminescente ou d'une matière première de substance luminescente et d'un sulfate de métal alcalino-terreux, dans leur état de coexistence, la teneur du sulfate se situant dans la plage allant de 5 à 95 % en poids.
  8. Procédé selon la revendication 7, dans lequel le frittage est conduit à une température se situant dans la plage allant de 550 à 1600°C et, de préférence, de 800 à 1550°C.
  9. Procédé selon la revendication 7, dans lequel la matière première de substance luminescente est une solution solide d'un activateur dans au moins un cristal-hôte.
  10. Procédé selon la revendication 7, dans lequel la substance luminescente ou la matière première de substance luminescente et le sulfate de métal alcalinoterreux sont mélangés mécaniquement, et dans lequel, de préférence, la substance luminescente ou la matière première de substance luminescente, étant une solution solide d'un activateur dans au moins un cristal-hôte, et le sulfate de métal alcalino-terreux sont mélangés de sorte que la teneur du sulfate de métal alcalino-terreux dans le mélange se situe dans la plage allant de 5 à 95% en poids, et, de préférence, de 10 à 95% en poids.
  11. Procédé selon l'une des revendications 7 à 10, dans lequel un composé contenant au moins l'un parmi le baryum, le phosphore et le bore est ajouté comme agent fondant.
  12. Procédé selon l'une des revendications 7 à 11, dans lequel une solution d'acide oxalique ou d'un oxalate soluble dans l'eau et une solution d'acide sulfurique ou d'un sulfate soluble dans l'eau sont ajoutés ensemble ou séparément à une solution aqueuse contenant à la fois un composé contenant au moins un élément de métal pour constituer une matrice de substance luminescente et un sel de métal alcalino-terreux, pour former des précipités de l'oxalate de l'élément de métal pour constituer la matrice de substance luminescente et le sulfate du métal alcalinoterreux, et en utilisant les précipités comme composant principal pour une matière première de substance luminescente, la matière première de substance luminescente est frittée.
  13. Procédé selon l'une des revendications 7 à 12, dans lequel le sulfate de métal alcalino-terreux se présente sous la forme d'un précurseur pour un sulfate de métal alcalino-terreux, qui comprend, de préférence, un composé de métal alcalino-terreux et de sulfate d'ammonium.
  14. Procédé selon l'une des revendications 7 à 13, dans lequel la substance luminescente ou la matière première de substance luminescente, étant une solution solide d'un activateur dans au moins un cristal-hôte et le sulfate de métal alcalino-terreux, sont mélangés d'une manière telle que le sulfate de métal alcalinoterreux est dispersé dans un solvant et, dans cet état, déposé sur la substance luminescente ou sur la matière première de substance luminescente pour former un matériau composite, qui est ensuite séché et fritté.
  15. Lampe fluorescente ayant une couche fluorescente qui contient une composition luminescente composée essentiellement de particules formées par fusion d'une substance luminescente et d'un sulfate de métal alcalinoterreux, telle que définie à l'une des revendications 1 à 14.
  16. Lampe fluorescente selon la revendication 15, dans lequel la couche fluorescente contient une matière émettant dans le bleu, ayant une longueur d'onde d'émission de pic se situant dans la plage allant de 430 à 475 nm, une matière émettant dans le vert ayant une longueur d'onde d'émission de pic se situant dans la plage allant de 520 à 560 nm, et une matière émettant dans le rouge, ayant une longueur d'onde d'émission de pic se situant dans la plage allant de 595 à 630 nm et, de préférence, additionnellement, une matière émettant dans le vert bleuté, ayant une longueur d'onde d'émission de pic de 480 à 500 nm, dans laquelle, de préférence, la matière émettant dans le rouge est composée d'une composition luminescente contenant des particules formées par fusion d'une substance luminescente de type oxyde de terre rare contenant de l'europium comme activateur et d'un sulfate de métal alcalino-terreux.
EP86117408A 1985-12-16 1986-12-15 Composition phosphorèe luminescente, procédé pour sa préparation et lampe fluorescente l'utilisant Expired - Lifetime EP0228010B1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP281146/85 1985-12-16
JP28114685 1985-12-16
JP8717486 1986-04-17
JP87174/86 1986-04-17
JP138343/86 1986-06-16
JP13834386 1986-06-16

Publications (2)

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EP0228010A1 EP0228010A1 (fr) 1987-07-08
EP0228010B1 true EP0228010B1 (fr) 1991-08-21

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EP86117408A Expired - Lifetime EP0228010B1 (fr) 1985-12-16 1986-12-15 Composition phosphorèe luminescente, procédé pour sa préparation et lampe fluorescente l'utilisant

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EP (1) EP0228010B1 (fr)
JP (3) JPH07116426B2 (fr)
KR (1) KR950009041B1 (fr)
BR (1) BR8607046A (fr)
DE (1) DE3681002D1 (fr)
HU (1) HU208990B (fr)
IN (1) IN168751B (fr)
WO (1) WO1987003611A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8823691D0 (en) * 1988-10-08 1988-11-16 Emi Plc Thorn Aquarium lighting
US5136206A (en) * 1990-05-14 1992-08-04 U.S. Philips Corporation Low-pressure mercury vapor discharge lamp suitable for illuminating a color original
JP3270073B2 (ja) * 1991-08-13 2002-04-02 化成オプトニクス株式会社 蛍光ランプ
JPH06264054A (ja) * 1993-03-11 1994-09-20 Nichia Chem Ind Ltd 陰極線管用蛍光体の製造方法
EP1127098A4 (fr) * 1998-08-27 2006-05-24 Superior Micropowders Llc Poudres de phosphore, procedes de fabrication de poudres de phosphore et dispositifs incorporant ceux-ci
EP1378556A3 (fr) 1999-07-23 2004-01-28 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Substance luminescente pour sources lumineuses et sources lumineuses correspondantes

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Publication number Priority date Publication date Assignee Title
NL169532C (nl) * 1974-05-06 1982-07-16 Philips Nv Elektrische gasontladingslamp.
JPS5832188B2 (ja) * 1976-03-29 1983-07-11 東洋インキ製造株式会社 熱螢光線量計用素子
JPS5397986A (en) * 1976-06-25 1978-08-26 Dainippon Toryo Co Ltd Fluorescent substance, and radiation image converter, discharge lamp and cathode-ray tube using the same
JPS5673847A (en) * 1979-11-19 1981-06-18 Nichia Kagaku Kogyo Kk Rare earth phosphor material

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KR950009041B1 (ko) 1995-08-14
JPS63102155A (ja) 1988-05-07
JP2656769B2 (ja) 1997-09-24
JP2757889B2 (ja) 1998-05-25
IN168751B (fr) 1991-06-01
DE3681002D1 (de) 1991-09-26
JPS6399287A (ja) 1988-04-30
BR8607046A (pt) 1988-02-23
WO1987003611A1 (fr) 1987-06-18
JPH07116426B2 (ja) 1995-12-13
HU208990B (en) 1994-02-28
EP0228010A1 (fr) 1987-07-08
JPS6399288A (ja) 1988-04-30
KR880700846A (ko) 1988-04-12
HUT46940A (en) 1988-12-28

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